most part, conceived with reference to magnitude; that into the accidents can never be entirely explicated, if, necessarily, essence is inherent in each of the existences.
Whence both these divisions are to be rejected, and only the division of the genus into species is approved, by which both the identity that is in the genus is characterized, and the diversity which subsists in the specific differences.
The species is always contemplated in a part. On the other hand, however, if a thing is part of another, it will not be also a species. For the hand is a part of a man, but it is not a species. And the genus exists in the species. For [the genus] is both in man and the ox. But the whole is not in the parts. For the man is not in his feet. Wherefore also the species is more important than the part; and whatever things are predicated of the genus will be all predicated of the species.
It is best, then, to divide the genus into two, if not into three species. The species then being divided more generically, are characterized by sameness and difference. And then being divided, they are characterized by the points generically indicated.
For each of the species is either an essence; as when we say. Some substances are corporeal and some incorporeal; or how much, or what relation, or where, or when, or doing, or suffering.
One, therefore, will give the definition of whatever he possesses the knowledge of; as one can by no means be acquainted with that which he cannot embrace and define in speech. And in consequence of ignorance of the definition, the result is, that many disputes and deceptions arise. For if he that knows the thing has the knowledge of it in his mind, and can explain by words what he conceives; and if the explanation of the thought is definition; then he that knows the thing must of necessity be able also to give the definition.
Now in definitions, difference is assumed, which, in the definition, occupies the place of sign. The faculty of laughing, accordingly, being added to the definition of man, makes
